Aluminum is ubiquitous in our everyday lives and, after steel and iron, it is the most widely used metallic material. If we consider the world’s resources, it is even the most common metal on Earth, albeit exclusively in bonded form. The manufacturing process is complex and energy-intensive. Aluminum is mainly extracted from bauxites, weathering products of limestone and silicate rock. The aluminum oxide produced from the bauxite using the Bayer process is transformed into aluminum (and oxygen) by melt flow electrolysis. 58 million tons of so-called primary aluminum are produced in smelters worldwide, by far the largest of which is in China, most recently (2022) 40 million tons per year.

In Germany, 3.3 million tons of crude aluminum were produced in 2022, most of which as recycled aluminum (almost three million tons). The production of aluminum is extremely energy intensive: 40 percent of the production costs of aluminum for cabins are incurred for electricity. Recycling, on the other hand, requires only five percent of the energy required for new production. The light metal can be integrated back into the material cycle − in other words, recycled − without loss of quality.

Due to its excellent forming properties and very high load-bearing capacity, aluminum is used in all areas of the economy. Nevertheless, there are some focus industries: According to the industry association Aluminum Deutschland, almost half of the aluminum products go to the transport industry (46 percent). The construction industry and packaging industry, on the other hand, use around 26 percent together. Industry, especially mechanical engineering, electrical engineering and the iron and steel industry, also uses a lot of aluminum, namely 19 percent of German aluminum production.

The most quantitatively important production area of the German aluminum industry is the semi-finished aluminum product, of which rolled and extruded products are the most important in terms of volume.

Pressed and drawn products are distinguished by profiles, bars, tubes and wires.

Another very important production area is aluminum die casting, i.e. finished components that are manufactured using different casting processes such as sand casting or die casting. Aluminum's low melting temperature makes it suitable for the production of cast parts. The main customer here is the automotive industry.

Aluminum is a very diverse material. Consumers know it, for example, as aluminum foil or a drink's can; other well-known products that catch your eye every day are household objects and appliances, furniture or facade systems.

If you take a closer look, it is apparent how ubiquitous aluminum is. This is mainly due to its versatility. Aluminum is a multi-functional raw material – light and stable, but tough. Its outstanding forming properties and high load capacity are impressive. Compared to steel, aluminum components have less than half the weight, with the same strength (around 60 percent less weight).

This is why aluminum – usually in the form of alloys – is always used where weight savings, stability and a protective function are required.

The most important applications of aluminum are:

Transport and traffic: Vehicle manufacturers value aluminum primarily for its lightness because it saves energy and fuel. The automotive industry uses it for bodies, chassis, engine blocks, cylinder heads, transmissions, doors, rims and wheels, among other things. Aluminum is also used extensively for bicycles, motorcycles, trains, ship and aircraft construction and even in aerospace.

Packaging and containers: In addition to the classic aluminum foil, aluminum is used as drinks or spray cans, bottles and tubes, as yogurt cup lids, coffee capsules, grill pans, medicine blister packaging and much more. It is ideally suited for use as packaging material: It is lightweight and therefore reduces transport costs, stays tight, withstands heat and cold and has no inherent taste. It is also often used as a container and system for the food and chemical industry.

Construction: Aluminum is of particular interest to the construction industry as a construction material for lightweight construction and as a functional material. It is easy to process, non-combustible and weather-resistant – making it ideal for windows and doors, facades, shower cubicles, fittings and handles, tubes, railings or wall and roof systems. Last but not least, the increased use of alternative energies has opened up further areas of application for the material aluminum, for example in wind and solar power plants or in heat exchangers.

Electrical engineering and mechanical engineering: Good to process, non-magnetic and above all good electrical and thermal conductivity – these properties are appreciated by mechanical engineering and the electrical engineering industry. Aluminum can therefore be found in capacitors, housings of electric motors, switch cabinets, tubes, high and low-voltage cables and busbars, in microchip production, in cooling fins and storage plates of IT installations, as a precision part, in cylinders and much more.

Household and leisure: If you look carefully in your home, you will discover aluminum almost everywhere. On the one hand because it is light and stable, and on the other because it has a particularly decorative and beautifully designable surface. It is considered to be a particularly “aesthetic” material. You can find it in the kitchen in pots, pans, crockery and cutlery, mobile phones and TVs, furniture, ladders, garden chairs and dozens of other everyday products.

How does aluminum behave when grinding?

Grinding aluminum is just like grinding any other metal. Nevertheless, the popular light metal has special properties in terms of its machining behavior and its physical properties.

Machinability: In general, the machinability of pure aluminum can be described as very good. You need significantly less energy than when machining steel, iron or copper, for example.

Lubrication tendency/clogging: Pure aluminum has low strength, is a very soft metal, and therefore tends to smear and form build-up edges during grinding. In the form of alloys, it becomes stronger or has a tougher machining behavior.

Conductivity: Aluminum has a high thermal and electrical conductivity. The thermal conductivity is four times higher than that of ferrous metals, which is why the material heats up faster during grinding – but the heat is distributed well throughout the workpiece.

Oxidation: The non-ferrous metal immediately forms a layer of oxidation that is only a few atoms thick on the surface, which protects against corrosion. These can be quickly removed by grinding. But within a very short time, in just a few minutes, it is formed again: This passive layer is "self-healing".

Compression: Because aluminum is so soft, it tends to compress massively. This is practical for fine work such as polishing, as a high-gloss surface can be created relatively quickly, which is even quite close to the chromium plate.

The entire range of grinding applications, from coarse to fine, is used throughout the entire production process for the surface processing of aluminum.

First, the deburring: Sharp edges and burrs on the cut edges must be removed in the same way as welds. In addition, weld seam preparation plays an important role. Abrasion of casting and bevelling of workpieces are also among the most important applications in the manufacture and processing of aluminum products.

Surface unevenness and imperfections are ground out during repair grinding or cleaning grinding. The final step is then finishing toward fine surfaces with a desired technical surface quality.

Depending on the workpiece size and requirements, aluminum is processed either by flat grinding, by backstand grinding (also known as a grinding trestle) - or with a hand power tool, such as an angle grinder or drum grinder.

With regard to the above-mentioned properties of aluminum – above all very good machinability, a strong tendency to smear and high thermal conductivity – it is good to follow a few basic machining or grinding rules.

If you want to achieve the highest possible stock removal when grinding aluminum, you start with a coarse grit size – with VSM ALU-X this is already possible from grit size P24 – and refine the grit size with every work step, for example in increments of 100. This allows the grinding marks from the previous steps to be ground out well.

ALU-X grinding wheels XF733 or the XK733X abrasive belt excel particularly in rough grinding work with high power over the entire grinding time and provide maximum stock removal with little chip adhesion. For intermediate sanding, for example, you can switch to ALU-X KK732F, an abrasive with versatile aluminum oxide abrasive grain on a flexible cotton fabric carrier. It is available in grit sizes from P80 to P600.

High cutting speed results in smaller chips. This reduces clogging and build-up of cutting edges. The cutting speed recommended by experts is vc = 35−40 m/s.

The choice of grinding pressure should always depend on the nature and possible alloys of the material. Particularly deep scratches usually require a high pressure at the beginning – but always with sensitivity, otherwise too much is quickly ground away and the effort for further processing is sometimes greater than before.

The grinding of aluminum requires constant cooling so that the surface does not burn or damage the material. Finer grit sizes tend to generate more friction and therefore higher temperatures in the workpiece. A cooling lubricant (KSS) can also help here.

Tip: Avoid contamination
aluminum cannot “rust” (it can, however, corrode), but metal chips or residues of other ferrous metals can be “worked” into the aluminum by using contaminated abrasives, and in the worst case, rust there. For this reason, abrasives with which aluminum has been processed may only be used for this purpose. The tools for aluminum processing should also only be used for this material. And last but not least, we recommend storing the different abrasives separately.

Tip: Carry out test grinding
Grinding aluminum requires a great deal of dexterity and, ideally, experience. Therefore, it is always advisable to test the pressure and speed for a new grinding operation on a pattern or a small area of the material before attempting a complete workpiece and large-area machining.

Ideal for non-ferrous metals such as aluminum: VSM ALU-X
VSM has developed a new series of abrasives to meet the specific requirements of grinding non-ferrous metals. VSM ALU-X, formerly known as VSM Stearate or Stearate Plus, combines two VSM technologies in one product: It is based on the proven VSM CERAMICS grinding technology with continuous self-sharpening. The ceramic grain abrasives with semi-open scattering stand for high stock removal with aggressive, fast cuts and long service life.

They are perfectly complemented by the additional layer VSM ALU-X for significantly better chip removal. It ensures consistent separation of the chip from the abrasive, which significantly reduces chip adhesion of the material to the abrasive grain – and effectively prevents annoying clogging. This allows ALU-X to optimize the processing of non-ferrous metals.

VSM CERAMICS with ALU-X is available as:

• Fiber disc XF733 in grit sizes 24, 36, 60 and 80: ideal for rough grinding with low to medium pressure
• Abrasive belt XK733X in grit sizes 24, 36, 40, 60, 80 and 120: optimized for rough grinding at medium pressure, also suitable for wet grinding

VSM aluminum OXIDE with ALU-X:

• The ALU-X series also includes the aluminum oxide abrasive belts KK732X, KK532F and KP532E. These products come in grit sizes from P36 to P600, making them true all-rounders. The grains produce a matt scratch pattern and are particularly recommended for contour machining.

Other VSM abrasives for aluminum machining:
VSM ACTIROX: The latest, removal-oriented generation of VSM abrasives is based on 100 percent geometrically shaped, upright VSM ceramic abrasive grains. These break down in a defined manner and continuously form new, extremely sharp cutting edges. The result is a particularly aggressive cut that provides market-leading stock removal when grinding aluminum – with up to 50 percent more stock removal than conventional ceramic grain abrasives. The AF799 fiber disc significantly reduces machining time and increases productivity, especially with hard aluminum alloys.

The grinding, brushing and polishing of aluminum produces fine dust that are highly combustible and – under certain circumstances, i.e. a sufficient mixture ratio with oxygen from the air and an ignition source – can even cause an explosion.

The legislator has therefore decided via the German Social Accident Insurance (DGUV) specific occupational safety regulations for handling aluminum and for “preventing dust fires and dust explosions”.

In DGUV Rule 109–001 is recommended for grinding, brushing and polishing aluminum, among other things:

• only with eye ear protection and in non-combustible clothing,
• reliably remove and keep away sources of ignition from the processing area,
• do not grind any spark-generating materials in the vicinity,
• avoid dust turbulence,
• use the wet method for processing if possible,
• make sure that the extraction system is always in operation, and
• clean workplaces regularly and with suitable means (industrial vacuum cleaners).

In addition, aluminum dust is considered to be a major health risk if inhaled and can cause lung diseases such as aluminosis, cancer or damage to the central nervous system. Workplaces should therefore not only be well-ventilated but must also be equipped with an extraction system. The use of suitable respiratory protection is also mandatory.